1. Field of the Invention
The present invention relates to a tandem color electrophotographic machine, and, more particularly, to margin alignment and plane-to-plane registration in a tandem color electrophotographic machine.
2. Description of the Related Art
Tandem color printing enables color electrophotographic printing to be performed by a printer at the same speed as black-and-white (mono color) electrophotographic printing. Such a tandem process utilizes four separate imaging devices to simultaneously create four separate latent images on four different photoconductive surfaces. Thus, all four colors can be imaged, developed, and transferred to the desired media at the same speed as a single color could be printed. Single color printers all implement techniques to align the top of the page, left margin, line length, and page length. In a tandem configuration, an additional difficult problem arises in registering each color image plane accurately relative to all the other color image planes. Manufacturers have been hesitant to produce tandem color laser printers because of the difficulty in maintaining alignment and plane-to-plane registration due to manufacturing tolerances.
What is needed in the art is a method of aligning the registration of all color planes in both the process direction (media direction of travel) and the scan direction (cross process direction).